Doses Of Ultraviolet Radiation Research Articles

A Spectrophotometric Method to Determine Minimal Erythema Dose for Ultraviolet Radiation in Human Skin.

Background/Objectives: Ultraviolet radiation (UVR) induces oxidative stress in the skin by generating reactive oxygen species (ROS), which can lead to inflammatory conditions including erythema (a sign of sunburn). This clinical study aims to develop an instrumental evaluation method to determine the minimal erythema dose (MED) for UVR. Methods: Fourteen human subjects aged 27 to 57 years (48.93 ± 8.54) participated in this study. Six subsites were designated on the test skin site of each subject and irradiated with UVR at different doses. The examiner visually assessed erythema, determining the 'visual MED'. Additionally, the a* value (a chrominance parameter presenting greenness to redness) was measured using a spectrophotometer as an indicator of erythema. The a* values of the UVR-irradiated subsites were compared to the non-irradiated control value, and the differences were referred to as Δa*. The Δa* value of the subsites irradiated with UVR at the 'visual MED' was referred to as the Δa*VMED for each subject. The mean of the Δa*VMED values of all subjects was chosen as a criterion value for the 'instrumental MED'. The 'instrumental MED' was defined as the lowest dose of UVR that causes an Δa* value equivalent to the criterion value. The 'visual MED' and 'instrumental MED' values of all subjects were subjected to correlation analysis. Results: The mean of the Δa*VMED values of all subjects was 1.88 ± 0.8. The means of the 'visual MED' and 'instrumental MED' values (in J m-2 unit) of all subjects were 300.14 ± 84.16 and 303.29 ± 77.99, respectively. In Pearson correlation analysis, the 'instrumental MED' and 'visual MED' values had a very strong positive correlation with each other (r = 0.864, p = 0.000). Conclusions: This study suggests that the instrumental evaluation method of MED based on the spectrophotometric measurement of the a* values can complement or replace the visual evaluation method and that this method will be useful in monitoring skin tolerance to oxidative stress affected by prooxidant factors and defensive factors.

A personalised and systematically designed adherence intervention improves photoprotection in adults with Xeroderma Pigmentosum (XP): Results of the XPAND randomised controlled trial.

Poor adherence to photoprotection in Xeroderma Pigmentosum (XP) increases morbidity and shortens lifespan due to skin cancers. To test a highly personalised intervention (XPAND) to reduce the dose of ultraviolet radiation (UVR) reaching the face in adults with XP, designed using known psychosocial determinants of poor photoprotection. A two-arm parallel group randomised controlled trial, including patients with sub-optimal photoprotection to receive XPAND or a delayed intervention control arm that received XPAND the following year. XPAND comprises seven one-to-one sessions targeting photoprotection barriers (e.g., misconceptions about UVR) supported by personalised text messages, activity sheets, and educational materials incorporating behaviour change techniques. The primary outcome, mean daily UVR dose-to-face across 21 days in June-July 2018, was calculated by combining UVR exposure at the wrist with a face photoprotection activity diary. Secondary outcomes were UVR dose-to-face across 21 days in August 2018, time spent outside, photoprotective measures used outside, mood, automaticity, confidence-to-photoprotect. Financial costs and quality-adjusted life years (QALYs) were calculated. 16 patients were randomised, 13 provided sufficient data for primary outcome analysis. The XPAND group (n=8) had lower mean daily UVR dose-to-face [0.03 SED (SD 0.02] compared to control (n=7) [0.36 SED (SD 0.16)] (adjusted difference=-0.25, p<0.001, Hedge's g=2.2). No significant between-group differences were observed in time spent outside, photoprotection outside, mood, or confidence. The delayed intervention control showed improvements in UVR dose-to-face (adjusted difference=-0.05, Hedge's g=-0.1) , time outside (adjusted difference=-69.9, Hedge's g=-0.28), and photoprotection (adjusted difference=-0.23, Hedge's g=0.45), after receiving XPAND. XPAND was associated with lower treatment costs (£-2642; 95% CI: -£8715 to £3873) and fewer QALYs (-0.0141; 95% CI: -0.0369 to 0.0028). XPAND was associated with a lower UVR dose-to-face in XP patients and was cost-effective.

Halocins and C50 Carotenoids from Haloarchaea: Potential Natural Tools against Cancer.

Haloarchaea are a group of moderate and extreme halophilic microorganisms, belonging to the Archaea domain, that constitute relevant microbial communities in salty environments like coastal and inland salted ponds, marshes, salty lagoons, etc. They can survive in stress conditions such as high salinity and, therefore, high ionic strength, high doses of ultraviolet radiation (UV), high temperature, and extreme pH values. Consequently, most of the species can be considered polyextremophiles owing to their ability to respond to the multiple extreme conditions characterizing their natural habitats. They cope with those stresses thanks to several molecular and metabolic adaptations. Thus, some of the molecules produced by haloarchaea show significantly different biological activities and physicochemical properties compared to their bacterial counterparts. Recent studies have revealed promising applications in biotechnology and medicine for these biomolecules. Among haloarchaeal biomolecules, rare natural pigments (C50 carotenoids) and small peptides called halocins and microhalocins have attracted attention worldwide due to their effects on animal and human commercial tumoral cells, apart from the role as antibiotics described for halocins or the immunomodulatory activity reported from C50 carotenoids like bacterioruberin. This review summarizes recent knowledge on these two types of biomolecules in connection with cancer to shed new light on the design of drugs and new therapies based on natural compounds.

Low Sun Exposure Is Associated with Both Progressive-Onset and Relapse-Onset Multiple Sclerosis Risk: A Case-Control Study

Background: Sun exposure has consistently been associated with multiple sclerosis (MS) onset, but case samples are predominantly relapse-onset MS (ROMS), and risk estimates have rarely been reported separately for ROMS and progressive-onset MS (POMS). We aimed to determine whether sun exposure prior to disease onset was associated with POMS and whether the effect differed between POMS and ROMS. Methods: This nationwide case-control study included 153 POMS cases, 204 incident ROMS cases, and 558 community controls with data from two separate datasets: the PPMS Study (2015–2021) and the Ausimmune Study (2003–2006). Information on time spent in the sun before the first MS symptom, skin phenotype, and sun protection behavior was collected. Satellite data on ambient ultraviolet radiation (UVR) were used to calculate cumulative UVR dose. Unconditional logistic regression was used with adjustment for covariates. Results: There were consistent dose-response associations, with higher levels of UVR exposure associated with a reduced risk of POMS, both for leisure-time and occupational UVR from age 6 to symptom onset. Associations were overall stronger for POMS than ROMS. For example, cumulative leisure-time UVR dose (per 100 kJ/m2 increment) was associated with POMS (aOR 0.93, 95% CI: 0.91–0.95) and the association was slightly weaker for ROMS (aOR 0.96, 95% CI: 0.94–0.99) for age 6 to symptom onset (test for interaction p < 0.001). Conclusions: Low levels of sun exposure, throughout the whole lifespan, are associated with an increased risk of POMS and ROMS onset. The sun effects are usually stronger for POMS than ROMS.

Photodynamic inactivation of antibiotic-resistant bacteria in whole blood using riboflavin photodynamic method.

Treating bacteremia caused by antibiotic-resistant bacteria is a global concern. Antibacterial photodynamic inactivation is a promising strategy to combat it. However, it's challenging to achieve the inactivation of antibiotic-resistant bacteria in whole blood because of its opacity and complexity. We investigated a riboflavin photodynamic method to effectively inactivate antibiotic-resistant bacteria in whole blood. Four strains of antibiotic-resistant bacteria were isolated, identified, and cultured in this research: methicillin-resistant Staphylococcus aureus (MRSA), pan-drug-resistant Acinetobacter baumannii (PDRAB), ESBLs-producing Escherichia coli (EPEC) and pan-drug-resistant Klebsiella pneumoniae (PDRKP). To simulate bacteremia, antibiotic-resistant bacteria was added into whole blood. Whole blood was treated using riboflavin photodynamic method with ultraviolet irradiation (308 nm and 365 nm). The ultraviolet irradiation dose was divided into 18 J/cm2, 36 J/cm2, and 54 J/cm2. Microbial count of antibiotic-resistant bacteria in whole blood was used for evaluating inactivation effectiveness. The roles of red blood cells, lymphocytes, coagulation factors, and platelets in whole blood were assessed. In results, inactivation effectiveness increased as the ultraviolet dose increased from 18 J/cm2 to 54 J/cm2. At the dose of 18 J/cm2, inactivation effectiveness of four antibiotic-resistant bacteria were more than 80%, while only 67% of MRSA. The antibacterial effect was enhanced by the combination of riboflavin photodynamic treatment and antibiotic. The red blood cell function was susceptible to ultraviolet dose. At the dose of 18 J/cm2, hemolysis rate was less than 0.8% and there was no change in levels of ATP and 2,3-DPG. At the same dose, the proliferation, cell killing, and cytokine secretion activities of lymphocytes decreased 20-70%; Factor V and Factor VIII activities decreased 50%; Fibrinogen and platelet function loss significantly but reparable. Consequently, we speculated that riboflavin photodynamic method with a ultraviolet dose of 18 J/cm2 was effective in inactivating four antibiotic-resistant bacteria in whole blood while whole blood function was preserved. We also provided a novel extracorporeal circulation phototherapy mode for treating bacteremia caused by antibiotic-resistant bacteria.

Determining the ultraviolet radiation dose experienced by aerosols using ultraviolet-sensitive dyes

Abstract. ​​​​​​​The application of ultraviolet (UV)-light-based air disinfection methods holds promise but also presents several challenges. Among these, the quantitative determination of the required UV radiation dose for aerosols is particularly significant. This study explores the possibility of determining the UV dose experienced by aerosols without the use of virus-containing aerosols, circumventing associated laboratory safety issues. To achieve this, we developed a model system comprised of UV-sensitive dyes dissolved in di-ethyl-hexyl-sebacate (DEHS), which facilitates the generation of non-evaporating and UV-degradable aerosols. For the selection of UV-sensitive dyes, 20 dyes were tested, and 2 of them were selected as being the most suitable, according to several selection criteria. Dye-laden aerosol droplets were generated using a commercial aerosol generator and subsequently exposed to UV-C radiation in a laboratory-built UV irradiation chamber. We designed a low-pressure impactor to collect the aerosols pre- and post-UV exposure. Dye degradation, as a result of UV light exposure, was then analyzed by assessing the concentration changes in the collected dye solutions using a UV-visible spectrophotometer. Our findings revealed that a UV dose of 245 mW s cm−2 resulted in a 10 % degradation, while a lower dose of 21.6 mW s cm−2 produced a 5 % degradation. In conclusion, our study demonstrates the feasibility of using aerosol droplets containing UV-sensitive dyes to determine the UV radiation dose experienced by an aerosol.

Evaluation of the abilities of atomic oxygen/ultraviolet resistance for the filled silicone rubber coating: Structures, properties, and aging mechanism

A series of experimental techniques were used to study the erosion-damage effect of a silica-filled silicone rubber coating exposed to simulated space environment (atomic oxygen and ultraviolet irradiation). The elastomer is known to be chemically and thermally stable, but there are insufficient data on its durability in the space environment. In the present work, atomic oxygen doses up to 3.8 × 1021 atoms·cm−2 and ultraviolet irradiation doses up to 360 equivalent sun-hours (ESH) were applied from Space Environment Simulation Measurement System, respectively. Since the aging and failure processes of the filled silicone rubber relate to different aspects of chemical structure and physics form, therefore, this study explored the use of chemical-mechanics methods to comprehensively evaluate the erosion-damage effect of materials. Morphology and chemical changes due to radiation were investigated by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS), and nanoindentation test probed surface mechanical properties changed with exposure dose. Results demonstrated that, with increased exposure time and irradiation-induced free radicals，the aggregation state and molecular chain structure of the silica-filled silicone rubber have changed, which caused an increase in surface hardness and modulus. Taken together, the results indicated that oxidative cross-linking was the dominant degradation mechanism under the irradiation dose in this paper.

Eradication of skin microbiota restores cytokine production and release in polymorphic light eruption.

Polymorphic light eruption (PLE) has been mechanistically linked to cytokine abnormalities. Emerging preclinical evidence posits the skin microbiome as a critical modulator of ultraviolet (UV)-induced cytokine expression, thereby influencing subsequent immune responses. This intricate relationship remains underexplored in the context of PLE. Hence, we investigated the differential responses between disinfected and non-disinfected skin following both single and repetitive exposures to solar-simulated UV radiation in patients with PLE. An experimental, half-body pilot study was conducted involving six PLE patients and 15 healthy controls. Participants' skin was exposed to single and multiple doses of solar-simulated UV radiation, both in disinfected and in non-disinfected skin areas. The co-primary outcomes were PLE score and cytokine expression in blister fluid analysed through OLINK proteomic profiling. Secondary outcomes were erythema, pigmentation, induction of apoptotic cells in vacuum-generated suction blisters, and density of infiltrate in skin biopsies of PLE patients. Among the 71 cytokines analysed, baseline expression levels of 20 specific cytokines-integral to processes such as apoptosis, inflammation, immune cell recruitment, cellular growth, and differentiation-were significantly impaired in PLE patients compared with healthy controls. Notably, skin disinfection reversed the observed cytokine imbalances following a single UV exposure at the minimal erythema dose (MED) level and exhibited even more pronounced effects after multiple UV exposures. However, no significant differences were evident in PLE score, erythema, pigmentation, or rates of apoptotic cell induction upon UV radiation. These findings provide evidence for UV-driven cytokine regulation by the skin microbiota and imply microbiome involvement in the PLE immune response.

Transcriptome analysis in mouse skin after exposure to ultraviolet radiation from a canopy sunbed.

Exposure to ultraviolet radiation (UV-R), from both natural and artificial tanning, heightens the risk of skin cancer by inducing molecular changes in cells and tissues. Despite established transcriptional alterations at a molecular level due to UV-R exposure, uncertainties persist regarding UV radiation characterization and subsequent genomic changes. Our study aimed to mechanistically explore dose- and time-dependent gene expression changes, that may drive short-term (e.g., sunburn) and long-term actinic (e.g., skin cancer) consequences. Using C57BL/6N mouse skin, we analyzed transcriptomic expression following exposure to five erythemally weighted UV-R doses (0, 5, 10, 20, and 40 mJ/cm2) emitted by a UV-R tanning device. At 96 h post-exposure, 5 mJ/cm2 induced 116 statistically significant differentially expressed genes (DEGs) associated with structural changes from UV-R damage. The highest number of significant gene expression changes occurred at 6 and 48 h post-exposure in the 20 and 40 mJ/cm2 dose groups. Notably, at 40 mJ/cm2, 13 DEGs related to skin barrier homeostasis were consistently perturbed across all timepoints. UV-R exposure activated pathways involving oxidative stress, P53 signaling, inflammation, biotransformation, skin barrier maintenance, and innate immunity. This invivo study's transcriptional data offers mechanistic insights into both short-term and potential non-threshold-dependent long-term health effects of UV-R tanning.

Chemical characterization of sunflower oil oxidized by UV and ozone with different degrees of oxidation and study of their antimicrobial action

Oxidation by the action of ozone takes place at high rates and involves the reaction of ozone molecules with fatty acid double bonds followed by the formation of stable oxidation products with biological activity. In the present work, a comparative study on sunflower oil oxidized by ultraviolet (UV) light and ozone was carried out. This study involved the chemical characterization of sunflower oil oxidized by UV irradiation and ozonation, in addition to assessing the germicidal activity of oxidized oils obtained under various conditions. The results indicated that under the conditions studied, the increase in the dose of UV irradiation did not produce significant changes in the level of oxidation of the oil. Ozonation promoted the formation of oxygenated compounds at higher rates, increasing in concentration as the applied dosage of ozone increased. The germicidal activity of the oils behaved similarly, with considerably higher activity found in the ozonized oils.

Inhibitory effect of UV and gamma radiation for fungal biodeterioration of concrete: A short-term study for sustainable conservation

The conservation of concrete-based deteriorated heritage buildings is a big challenging issue worldwide including in India. This study focused on to prevent fungal biodeterioration in concrete using UVC and gamma radiation. M20 graded concrete cubes (5 cm × 5 cm × 5 cm) were infected with Aspergillus tamarii, which was isolated from a 200 years old historic heritage building. M20 signifies a mixture of cement, sand and aggregate (1:1.5:3), made in such a way that the concrete cube has a compressive strength of 20 N/mm2 when examined after 28 days of curing. The fungal growth appeared clearly as calcium oxalate crystals in the Scanning Electron Microscope (SEM) photographs. Several doses of UVC and gamma radiation were applied on concrete cube. The changes in concrete properties were examined after 30 days in terms of weight, compressive strength, Fourier Transform Infrared Spectroscopy (FTIR) and micro Energy Dispersive X-ray Fluorescence (EDXRF). The results exhibited that compressive strength of control (non-infected and non-irradiated), biodeteriorated (infected), UVC (625 µw/cm² × 300 s) and gamma (0.5 KGy) irradiated infected (inhibition) concrete cubes were 19.74 ± 0.46, 18.88 ± 0.43, 20.20 ± 0.34 and 19.93 ± 0.20 N/mm2 respectively whereas negligible weight losses were observed for inhibition cubes compared to biodeteriorated ones. Calcite (1400, 874 and 705 cm−1), one of the major functional band present in concrete became weak after getting infected by Aspergillus tamarii and strong for inhibition samples irradiated with the above doses. The EDXRF analysis exhibited that mass percentage of calcium ions of the biodeteriorated concrete cubes (49.88 ± 0.65%) was lower than that of UV (75.75 ± 0.16%) and gamma (70.95 ± 0.30%) irradiated infected or inhibition concrete cubes. Altogether, the efficacy of the recommended inhibitory dose of ultraviolet and gamma radiation against concrete deterioration in the field of conservation of heritage building was observed to be positive.

Germicidal Efficiency of 272 nm LED in Relation to the Hospital Strain of Klebsiella Pneumoniae

Relevance. Currently, the use of ultraviolet (UV) radiation for the disinfection of objects and the treatment for infectious diseases is considered as a promising alternative to chemical biocides and antibiotics. Shortwave — UV-C and UV-B -light emitting diodes (LED) are a relatively new type of UV radiation sources and potentially able to meet the requirements of current medical technologies. However, their possibilities for the treatment of wounds and infectious diseases have not been practically researched to date, which determines the relevance of experiments aimed at studying the biocidal and therapeutic properties of shortwavelength UV LEDs.Purpose. OF STUDY To evaluate the bactericidal efficacy of 272 nm LED radiation against hospital strains of Klebsiella pneumoniae bacteria characterized by multidrug resistance.Materials and Methods. The studies were carried out with an experimental sample of the LED apparatus for UV irradiation. In the irradiator of the device, 5 LEDs are installed with a maximum radiation at a wavelength of 272 nm and a total electrical power of 10 watts. The UV radiation dose achieved in one irradiation session (12 seconds) at a distance of 10 cm from the irradiator was 8 mJ/cm2 . In the experiments, a hospital strain of the bacterium Klebsiella pneumoniae, isolated from the patient’s blood, was used. The strain was characterized by multidrug resistance. A daily culture suspension of K. pneumoniae with a concentration of 108 CFU/ml in a volume of 100 µl was transferred into a Petri dish with a diameter of 9 cm with meat-peptone agar and evenly distributed over a surface with a diameter of 8 cm. Petri dishes were irradiated from a distance of 10 cm from the irradiator. The change in the dose of UV irradiation from 4 to 80 mJ/cm2 was carried out by varying the exposure time. Studies were carried out in 4 repetitions at each dose. After irradiation, the experimental and control (without irradiation) Petri dishes were placed in a thermostat at 37ºC for 24 hours, then the grown colonies were counted. A total of 60 experiments were carried out.Results. As a result of the research, it was shown that the LED device based on five 272 nm diodes provides deep and prompt disinfection of the surface from hospital strains of K. pneumoniae bacteria characterized by multidrug resistance. A dose of UV radiation of 8 mJ/cm2 reduces surface contamination with K. pneumoniae bacteria by more than a million times (decontamination efficiency over 99.9999%). At doses less than 10 mJ/cm2 , the efficiency of the 272 nm LED device in terms of inactivation of K. pneumoniae bacteria is 3–4 times higher than the bactericidal efficiency of mercury lamps.Conclusion.The prospects of using UV devices based on LEDs with a maximum radiation at a wavelength of 272 nm in systems for the operational disinfection of massively contaminated surfaces, potentially including wound surfaces, have been shown.

Эффект синергизма для управления посевными качествами семян люцерны изменчивой с элементами нейросети для контроля дозы УФО

The article presents studies to identify the greatest synergy effect for managing the sowing qualities of alfalfa seeds of variable Victoria with the use of neural network elements to control the dose of ultraviolet irradiation. The synergistic effect occurs when the seeds are simultaneously exposed first to ultraviolet radiation and then to a silicon-containing preparation of nanosilicon, or first to treatment with a preparation of NanoSilicon, and then to ultraviolet radiation. In both cases, changes in the sowing qualities of seeds were observed. The seeds were irradiated on a mobile LED UV irradiation unit using end-to-end digital energy-saving technologies with neural network elements to control the dose of UFOs with a VEML6070 digital sensor from the manufacturer Vishay Semiconductors. The TKS– ABC device measured the energy illumination of UV LEDs at a height of 70 mm, which showed that UV-A radiation is 95.67% at an average energy illumination of 3.137 W/m2, UV-B radiation is 3.41% at 0.112 W/m2 and UV-C radiation is 0.91% at 0.030 W/m2. The conducted studies have revealed that the greatest synergistic effect for managing the sowing qualities of alfalfa seeds occurs when alfalfa seeds are treated first with a nanosilicon preparation, and then with UFOs. As a result of the management of the sowing qualities of alfalfa seeds, which is involved in the implementation of the proposed sequence of pre-sowing seed treatment, an increase in laboratory germination was obtained by 6% at HCR05 – 4%; the length of the sprout up to 2.4 cm and the root up to 1.5 cm; the degree of development of seedlings up to 3.0 points and growth strength up to 29.8%. Keywords: ALFALFA VARIABLE, LABORATORY GERMINATION, DEGREE OF SEEDLING DEVELOPMENT, GROWTH VIGOR, SYNERGISM, ULTRAVIOLET IRRADIATION DOSE, DIGITAL CONTROL SYSTEMS

Smart City and the digital measurement of solar ultraviolet radiation in Outdoor workers in the City of Lisbon

Abstract The growing incidence of skin cancer over the years has made it a significant public health problem. However, technology can be used to tackle the skin cancer which is highly preventable, mainly through reduced exposure to solar ultraviolet radiation (UVR). Digital services can be used to promote individual and collective protective measures and interventions. Specifically, there is an opportunity when the exposure is intermittent or continuous, and occurs in an occupational or leisure setting. We are using a digital platform to contribute to raising public and policy awareness on solar UVR-inflicted occupational skin cancers in the municipality of Lisbon. The digital platform is performing direct measurements of the solar UVR dose received by outdoor workers. Results will likely contribute to further understanding the risk estimates for keratinocyte cancer estimations in this population. The digital platform integrates a personal electronic dosimeter (GENESIS-UV system) to assess occupational solar UVR doses of gardeners, masons, and gravediggers of the municipality of Lisbon. Two hundred and ten outdoor workers were selected to wear the dosimeter for 1 month each, between April and October during their daily working hours. The digital platform that offers private access to information through dashboard visualization provided information for the outdoor workers and facilitate communication with the participants. Study data provides the outdoor workers with information on their personal solar UVR exposure during their working hours and an estimate of their risk of developing skin cancer. The results prospectively should flow into the design of adequate prevention campaigns for skin cancer in outdoor workers.

Ultraviolet sun exposure and sun protection behaviors in outdoor rock climbers

BackgroundOverexposure to sunlight and sunburn are the main preventable causes of skin cancer. Outdoor sports are associated with significant levels of sunlight exposure.AimsWe sought to quantify the sun radiation exposure received by outdoor rock climbers and assess their sun exposure habits, sun protection behaviors, attitudes, and knowledge regarding skin cancer.MethodsFrom April to June 2021, outdoor rock climbers contacted via email completed an online validated self-reported questionnaire on sun related habits, behaviors, attitudes and knowledge. As a pilot trial, ten participants wore a personal dosimeter during two outdoor climbing weekends in May and November 2021. Ambient ultraviolet radiation (UVR) was also recorded.ResultsA total of 217 outdoor rock climbers (103 women), mean age 36.8 ± 8.8 years (range 20–70 years) and median climbing practice per week of 8 h (IQR 7.5) were studied. Two in three (65.9%) participants reported at least one sunburn event during the previous rock climbing season. Of the survey respondents, 49.3% reported using sunscreen with SPF ≥ 15, 47% wore sunglasses, and 14.3% indicated they reapplied sunscreen every two hours. The median personal UVR dose measured during the two outdoor climbing weekends analyzed was 5.2 (IQR 1.8) and 8.8 (IQR 1.1) standard erythemal doses, respectively.ConclusionsThe high rates of sunburn, the elevated personal UVR measured and the clearly insufficient sun protection practices followed during rock climbing together with unsatisfactory attitudes towards tanning reveal the need to develop explicit sun protection campaigns and educational strategies to reduce the risk of skin cancer among the athletes studied.Graphical abstract

Photoirradiation‐Gated Excitation‐Dependent Room‐Temperature Phosphorescence in Through‐Space Charge Transfer Molecules

AbstractOrganic materials showing reversible changes in persistent room‐temperature phosphorescence (RTP) upon exposure to external stimuli have attracted considerable attention in recent years. One potentially groundbreaking development in this area is the introduction of the gating concept for organic persistent RTP materials. This refers to a material where a desired responsive ability only occurs when it is triggered by a specific stimulus, but it remains a formidable challenge. In this study, photoirradiation‐gated excitation‐dependent (Ex‐De) persistent RTP is achieved. A series of molecules, triphenylphosphine and carbazole derivatives connected through flexible carbon chains, are designed and prepared. Upon removal of ultraviolet (UV) irradiation, all these compounds doped polyvinyl alcohol (PVA) films exhibit obvious blue or green afterglow RTP. Among them, (2‐(9H‐[3,9′‐bicarbazol]−9‐yl)ethyl)triphenylphosphonium bromide (TPP‐2C‐Cz) doped PVA film initially exhibits blue persistent RTP after removal of 300 nm excitation but no RTP upon ceasing 365 nm irradiation. Interestingly, upon UV irradiation with a power density of 0.05 W cm−2 (UVA) for 50 min, the Ex‐De RTP behavior of TPP‐2C‐Cz doped PVA film is activated. Eventually, photoirradiation‐gated Ex‐De afterglow emission will be used for a wide range of applications, including the quantitative determination of UV irradiation dose and the permanent record of UV irradiation history, and read on‐demand.

Photochromic Uranyl-Based Coordination Polymer for Quantitative and On-Site Detection of UV Radiation Dose.

A highly sensitive detection of ultraviolet (UV) radiation is required in a broad range of scientific research, chemical industries, and health-related applications. Traditional UV photodetectors fabricated by direct wide-band-gap inorganic semiconductors often suffer from several disadvantages such as complicated manufacturing procedures, requiring multiple operations and high-cost instruments to obtain a readout. Searching for new materials or simple strategies to develop UV dosimeters for quantitative, accurate, and on-site detection of UV radiation dose is still highly desirable. Herein, a photochromic uranyl-based coordination polymer [(UO2)(PBPCA)·DMF]·DMF (PBPCA = pyridine-3,5-bis(phenyl-4-carboxylate), DMF = N,N'-dimethylformamide, denoted as SXU-1) with highly radiolytic and chemical stabilities was successfully synthesized via the solvothermal method at 100 °C. Surprisingly, the fresh samples of SXU-1 underwent an ultra-fast UV-induced (365 nm, 2 mW) color variation from yellow to orange in less than 1 s, and then the color changed further from orange to brick red after the subsequent irradiation, inspiring us to develop a colorimetric dosimeter based on red-green-blue (RGB) parameters. The mechanism of radical-induced photochromism was intensively investigated by UV-vis absorption spectra, EPR analysis, and SC-XRD data. Furthermore, SXU-1 was incorporated into an optoelectronic device to fabricate a novel dosimeter for convenient, quantitative, and on-site detection of UV radiation dose.

Thermal compensation reduces DNA damage from UV radiation

Increases in ultraviolet radiation (UVR) correlate spatially and temporally with global amphibian population declines and interact with other stressors such as disease and temperature. Declines have largely occurred in high-altitude areas associated with greater UVR and cooler temperatures. UVR is a powerful mutagenic harming organisms largely by damaging DNA. When acutely exposed to UVR at cool temperatures, amphibian larvae have increased levels of DNA damage. Amphibians may compensate for the depressive effects of temperature on DNA damage through acclimatisation, but it is unknown whether they have this capacity. We reared striped marsh frog larvae (Limnodynastes peronii) in warm (25 °C) and cool (15 °C) temperatures under a low or moderate daily dose of UVR (10 and 40 μW cm−2 UV-B for 1 h at midday, respectively) for 18–20 days and then measured DNA damage resulting from an acute high UVR dose (80 μW cm−2 UV-B for 1.5 h) at a range of temperatures (10, 15, 20, 25, and 30 °C). Larvae acclimated to 15 °C and exposed to UVR at 15 °C completely compensated UVR-induced DNA damage compared with 25 °C acclimated larvae exposed to UVR at 25 °C. Additionally, warm-acclimated larvae had higher DNA damage than cold-acclimated larvae across test temperatures, which indicated a cost of living in warmer temperatures. Larvae reared under elevated UVR levels showed no evidence of UVR acclimation resulting in lower DNA damage following high UVR exposure. Our finding that thermal acclimation in L. peronii larvae compensated UVR-induced DNA damage at low temperatures suggested that aquatic ectotherms living in cool temperatures may be more resilient to high UVR than previously realised. We suggested individuals or species with less capacity for thermal acclimation of DNA repair mechanisms may be more at risk if exposed to changing thermal and UVR exposure regimes.

Disinfection of Surfaces Contaminated with SARS-CoV-2 Coronavirus by UV Radiation of Low-Pressure Mercury-Vapour Lamp

The aim of the work was to determine the effective ultraviolet (UV) doses required for the disinfection of surfaces contaminated with the SARS-CoV-2 coronavirus using a low-pressure mercury lamp. Materials and methods. To carry out prompt disinfection of surfaces, a specially designed source of UV radiation with a power of 7.5 W at a wavelength of 254 nm in the form of a portable flashlight was employed, which has a high efficiency of UV radiation output and the possibility of long-term autonomous operation from a compact battery. In the studies, a suspension culture of the SARS-CoV-2 coronavirus with biological activity of 5.3∙106 PFU/ml was used. The objects of testing were plastic Petri dishes (disposable) and office paper (grade C, density 80 g/m2 ). Results and discussion. Doses of UV radiation that provide disinfection of surfaces contaminated with the COVID-19 pathogen with an efficiency of 99.0 % (paper) to 99.95 % (plastic) have been determined. The results obtained make it possible to recommend a portable UV irradiator for use in the practice of preventive measures to combat the spread of the disease caused by the SARS-CoV-2 coronavirus.

Performance Comparison of SONOS-Type UV TD Sensor Using Indium Tin Oxide-Aluminum Oxide-Zirconia Aluminum Oxide-Silicon Oxide-Silicon and Indium Tin Oxide-Aluminum Oxide-Hafnium Aluminum Oxide-Silicon Oxide-Silicon

This study compares the performance of two types of capacitive devices, indium tin oxide-aluminum oxide-zirconia aluminum oxide-silicon oxide-silicon (IAZAOS) and indium tin oxide-aluminum oxide-hafnium aluminum oxide-silicon oxide-silicon (IAHAOS), as silicon-oxide-nitride-oxide-silicon (SONOS) non-volatile memory (NVM) total dose of ultraviolet radiation (UV TD) sensors. Results show that IAZAOS with zirconia aluminum oxide as the charge-trapping layer outperforms IAHAOS with hafnium aluminum oxide for a UV TD sensor. After exposure to UV TD irradiation of 100 mW·s/cm2, the threshold voltage (VT) change of IAZAOS is almost 1.25 times that of IAHAOS. The study also found that annealing can significantly improve the response performance of IAZAOS UV TD sensors. Furthermore, IAZAOS devices with partially smaller nanocrystals in the charge-trapping layer greatly enhance the response of SONOS-type UV TD sensors. The study also compared the constant voltage stress-induced leakage current (CVSILC) and found that the CVSILC for annealed IAZAOS devices is 1000 times smaller than that of IAHAOS devices. Moreover, the IAZAOS-I2Z2 exhibits a superior performance regarding irradiation/refresh cycle endurance as compared to the IAHAOS-I2H1 device. These findings suggest that IAZAOS capacitive devices have superior performance and potential for use in SONOS-type UV TD sensors.